Sorry to hear about your dad.
Wrt the issue at hand: yes the cancer was found as an incidental finding on a scan performed for another indication (shoulder pain) -> the question remains whether your father benefitted from finding the cancer. This is seldomly the case.
Anecdotally, everything is possible but on a population scale, actual survival benefit is rare - whereas suffering from the downsides is not - even if only counting unnecessary healthcare cost and time wasted.